1. INTRODUCTION

These are exciting times to be working on any aspect of studies of
galaxies at high redshift whether observational or theoretical.
Most would agree that the current period represents something of a
golden era in the subject.
Figure 1 shows the increasing
extent to which articles concerned with galaxy evolution dominate
the published literature over the past 25 years (gauged
xenophobically I'm afraid by keyword statistics only in two North
American journals).

Figure 1. The remarkably rapid growth in galaxy
evolution studies: the fraction of the ApJ and AJ literature
containing the key word `galaxy evolution' over the past 25 years.
The inset shows the marked decline in the use of galaxies as
probes of the cosmological parameters during 1970-1980 (after
Brinchmann, Ph.D. thesis 1998).

One often hears claims that a subject undergoing spectacular
progress is one that is nearing completion (c.f.
[Horgan 1997]).
After all, the rise in Figure 1 clearly cannot continue
indefinitely and fairly soon, it could be argued, we will then
have solved all of the essential problems in the subject. As if
anticipating this, a theoretical colleague gave a recent
colloquium at my institute entitled Galaxy Formation: End of
the Road!

Consider the evidence. Observationally we may soon, via
photometric redshifts, have determined the redshift distribution,
luminosity evolution and spatial clustering of sources to
unprecedented limits. If one accepts photometric redshifts are
reliable, the rate of progress in the traditional pursuit of
N(m, color, z) is limited solely by the field of view of the
telescope and the exposure times adopted. Panchromatic data
matching that obtained with optical and near-infrared telescopes
from SIRTF, FIRST, and ALMA will also enable us unravel the cosmic
star formation history
SFR(z)
to unprecedented precision
([Madau et al 1996,
Blain et al 1999]).
It has already been claimed that
the above data, e.g. N(m, color, z) and
SFR(z),
can be
understood in terms of hierarchical models of structure formation
where galaxies assemble through the cooling of baryonic gas into
merging cold dark matter halos (CDM,
[Kauffmann
et al 1994,
Baugh et al 1998,
Cole et al 2000a]).

The word `concordance' was recently coined astrophysically in an
article reconciling different estimates of the cosmological parameters
([Ostriker
& Steinhardt 1996]). Such concordance in our
understanding of galaxy evolution is a natural consequence of
semi-analytical theories whose sole purpose is to explain the `big
picture' as realised with the extant galaxy data. In this series
of lectures I want to show that we have our work cut out for some
considerable time! Exciting progress is definitely being made, but
observers must rise to the challenge of testing the fundamentals
of contemporary theories such as CDM and theorists must get ready
to interpret qualitatively new kinds of data that we can expect in
the next decade.

These lectures are intended for interested graduate students or
postdocs entering the field. There is an obvious observational
flavor although I have tried to keep in perspective an ultimate
goal of comparing results with recent CDM predictions. The bias is
largely to optical and near-infrared applications; there is
insufficient space to do justice to the rapidly-developing
contributions being made at sub-millimetre, radio and X-ray
wavelengths which other contributors at this winter school will
cover in detail.